The present invention relates to a random accessible filing system for producing continuous signals, and particularly pertains to a filing system equipped with magnetic discs and adapted to select, through random access, the signals recorded with the address on the magnetic discs; said signals to be prepared and fed out as a series of signals.
Today, from every broadcasting station, signals of commercials (hereinafter referred to as CMs) are put out during the intermissions between programs, and the number of CM messages is very large, amounting, for example, to about 400 kinds per day, or about 1,000 per week on the average. These broadcasting stations should as part of their daily business in order to feed out the continuous signals for producing the CM messages, select and edit CMs to be fed out daily in the feed-out sequence from among the CMs of about 2,000 kinds of stock tapes with a 20 second average run. If done manually, this task is really intolerable.
In some broadcasting stations, this work is performed automatically by mechanizing the necessary operations for the CM feed-out. One approach is that the required CMs (for example, about 2,000 kinds) are registered on multitrack tape recorders capable of an automatic search function; then, the information designating the CMs to be fed out is received by the use of a typewriter or tape reader, etc., and in that sequence, the specified CMs are successively outputted by implementing the automatic search function. Outside, this output is recorded on another tape recorder, so that the edited tape unified in the feed-out sequence of the CMs may be obtained.
The disadvantage of this method is that a long time is taken because the search is made by the travel of the tape, and must be conducted successively from one end of the tape. Thus, the edited tape should always be prepared once in the unified form, and then, fed out. Accordingly, it is impossible to perform the search and automatic feed-out in real time. Moreover, any additions, revisions, etc., if required, after the unified edited tape is prepared, are very difficult to make. Besides, because analogue type recording has been adopted, deterioration with time resulting from transcriptions, etc., of the CM record tapes, deterioration from rerecording and other deteriorations in signal characteristics are pronounced.
Among the other methods for automating the CM feed out is the method of real time automatic feed-out, in which the required CMs are automatically sought and fed out in keeping with the required timing. In one method presently in practical use, an arbitrary tape recorder is selected from among cartridge type tape recorders prepared in the required number (about 1,000 kinds), the use of a switcher to feed out the CM. This method requires a large scale system, and large numbers of tape recorders must be used, so that it is less reliable. Moreover, as this method is also based on an analog type recording, the deterioration with time of the recording signal characteristics, deterioration from rerecording, etc., are unavoidable.
As a method for realizing CM automatic feed-out devices capable of operation with high efficiencies and speeds by overcoming the difficulties in the two methods mentioned above, the approach of digitally recording the audio signals on digital magnetic discs may be considered useful. However, to achieve the digital recording of the voice data of about 1,000 kinds and with such high quality as required by the standards for broadcasting, magnetic disc devices with as high a capacity as several hundred mega-bites are necessary. Since in such large magnetic disc devices, data transfer at high speeds is required, the data is transferred generally by clock pulses at high frequency. Accordingly, for the control of such large magnetic discs, large computers capable of operation at high data transfer speeds are necessary. Such computers are not suited for the above-described purpose by reason of their high prices and large sizes, etc.